The Sunflower Star
Taxonomy: Phylum Echinodermata
Range: This species of sea star can be found from the Aleutian Islands in Alaska to
Isla Todos Santos off the California peninsula in Mexico. Steamboat Island, WA
Habitat: It can live from the low intertidal depth all the way to around 435 m. It
lives in rocky shores as well as sandy or gravelly substrata in deeper ranges.
Morphology: Adults have around 20-24 arms or rays depending on if the organism has lost any. Pentamerically radial. Can reach a diameter of 1m. Colors vary from yellow, brown, purple, or orange with violet or purple tufts. Has a mesodermally derives calcareous endoskeleton, benthic, errant, unique water vascular system with hydrolically operated flesh, no cephalization. Achieve locomotion by podia which are extensions of the tube feet. Can reach speeds up to 3 meters an hour.
Predators and Prey: The Alaskan king crab is a predator to P. helianthoides. This star is carnivorous and is known to eat mussels, clams, oysters, urchins, sea cucumbers, sand dollars, and dead fish. Pycnopodia helianthoides is a feared predator and can evoke escape responses from a variety of organisms. Its favorite meal is bivalved mollusks. Once the star captures its prey it spreads its stomach over the animal and secretes enzymes that turn their prey to soup before they suck it into their stomach.
Reproduction: Asexually- Fissiparity (fission)
Sexually- Dioecious, hermaphroditic, gametogenesis
Prepared by Aaron Shepard.
Program Invertebrate Zoology,
The Evergreen State College.
1) Brusca, R. C., Brusca, G. J., Invertebrates 2nd ed. Sinauer Associates 2003. pg. 801-803.
2) Kozloff, E.N. 1973. Seashore Life of Puget Sound, the Strait of Georgia and the San Juan Archipelago. University of Washington Press, Seattle.